Widespread polychlorinated biphenyl (PCB) contamination of the environment and the detection of these compounds in the tissues of man and lower animals indicate the health significance of human exposure to PCBs. The only data available on the effects of PCB in man include observations of external lesions and clinical signs and symptoms following acute exposure from industrial accidents. Thus there is a need to assess chronic effects which result from low level exposure to PCBs, particularly the following: modifications in reproductive capabilities; embryonic, fetal and neonatal development; endocrine, liver and gastrointestinal function, and immunologic competence of the exposed subjects. Since this research is not possible in man, and since lower animals show marked variations in their responses to PCBs, the subhuman primate is the animal of choice. Adult male and female monkeys will be exposed to low levels of PCBs over a five year period and will be clinically evaluated at regular intervals. The effect of PCBs on fertility of the male and female will be carefully evaluated. Throughout gestation the pregnant female wll be observed for signs of impending difficulties. Aborted fetuses, stillborn and newborn infants will be examined for teratogenic abnormalities. Physical and neurological development will be determined throughout infancy, adolescence and early adulthood. When sexual maturity is reached, the F1 generation will be mated and observed throughout pregnancy. The F2 generation will be carefully examined for mutagenic alterations. After the second year, one half of the adult animals will be removed from the PCB diet in order to determine reversibility of lesions and rate of recovery. Previous acute studies on subhuman primates delineated gastric, hepatic and skin alterations. As these and other tissue alterations are discovered, biochemical, histological and ultrastructural evaluations of these changes will be conducted in order to obtain a better understanding of the pathogenesis of PCB intoxication.